Recently, efforts have been made to reduce energy consumption and greenhouse gas emissions. In this respect, in order to reduce energy consumption in the building sector accounting for about 30% of total energy consumption in Korea, studies on novel compositions and insulating materials comprising the same have been actively conducted.
Insulating materials are used to minimize the transfer of heat and can be broadly divided into organic insulating materials and inorganic insulating materials. In Korea, inorganic insulating materials account for about 70% of insulating materials, and inorganic insulating materials are frequently used in applications requiring flame retardant materials.
Table 1 below summarizes various insulating materials and the properties, workability and toxicity of each insulating material.
TABLE 1Organic materialsInorganic materialsPolystyrenePolyurethaneGlass woolRock wool(foamed/compressed)(foamed/hard)Polyethylene (foamedPropertiesHeat-insulatingHeat-insulatingInsulatingInsulatingHeat/electricallySound-Sound-WaterproofWaterproofinsulatingabsorbingabsorbingAdhesiveAdhesiveWaterproof/chemical-DurableDurableFlame retardantFlame retardantresistantWater-repellantWater-repellantAdhesive/impact-resistantFlame retardantSafe temperature3006007010080for use (° C.)Thermal 0.039 0.0390.023-0.0390.022-0.025 0.03conductivity(kcal/mh ° C.)Water absorptionAbsorbingAbsorbingAbsorbing a little waterAbsorbing aNot absorbing waterwaterwaterlittle waterNoncombustibilityNoncombustibleNoncombustibleSelf-extinguishableSelf-InflammableextinguishableWorkability1. easy to treat joints1. difficult to treat joints1. the same as1. difficult to treat2. giving a tingling feeling to2. difficult to treat bentpolyethylenejointsworkersportions and surfaces2. expanded in2. difficult to treat3. avoided by workers3. easy to usework placebent portions andsurfaces3. easy to useToxicityGenerating no toxic gasGenerating toxic gases such as CO and CO2Capable of causing lung cancerOthersHeat and coldLow pricedInsulating function isUsed ininsulationHeat and coldreduced with therefrigeratinginsulationpassage of time in usedevices and thelikeHigh pricedNot constantlysuppliedImpossible torecycleOther insulatingFoam glass, ALC calciumPelt, plant fibers, foam rubber, urea resin, etc.materialssilicate, gypsum board,vermiculite, diatomite, etc.
Referring to Table 1, in the glass wool that is a typical inorganic insulating material, the sealed air layer between the glass fibers provides insulation. The glass wool is noncombustible and absorbs sound, and the effective thickness and insulation property of are not decreased by compression. However, it absorbs water, making it needed to provide a separate damp-proof layer, and gives a tingling feeling to workers.
The polystyrene that is an organic insulating material has a high insulation effect, is lightweight and is easy to use. However, it is weak against UV rays, and is likely to generate toxic gases, which are fatal to the human body, when it catches fire.
In addition, the polyurethane that is another organic insulating material has shortcomings in that the volume and thermal conductivity thereof are reduced after application thereof and in that it is likely to generate toxic gases when it catches fire.
Among insulating materials which are used as core materials in sandwich panels or fire doors, organic insulating materials have excellent insulation properties, but are weak against fire. Due to this problem, these organic insulating materials have no commercial value or are used in limited applications. In addition, inorganic insulating materials have a problem in that they require high-temperature processes, which increase process costs.
Meanwhile, methods of manufacturing ceramic insulating materials using ceramic compositions include a foaming method, which uses gel casting and double emulsion, and a foaming method which uses fly ash, clay and the like as main materials and calcium carbonate (CaCO3) and carbon as foaming agents. Porous insulating materials manufactured by such methods have porous structures which vary depending on the composition of raw materials, physical properties such as particle size, and the kind and content of foaming agent.
In addition, there is a double-calcination method which uses waste glass as a main material and iron trioxide (Fe2O3) as a foaming agent and in which calcination is repeated to form open pores. A porous insulating material manufactured by this method has small pores.
However, these methods have problems in that specific materials are used in large amounts or a temperature of 1000° C. or higher is generally required, except for modified processes comprising pressurization.